A methodology for scaling a small-scale energy exchanger performance results to a full-scale energy exchanger

Abstract

In energy exchangers, heat and moisture simultaneously transfer between two fluids (i.e. liquid and air) which are directly in contact or separated by a semi-permeable membrane. The membrane is permeable for water vapor but impermeable for liquids. Testing a full-scale energy exchanger is often expensive and time consuming, so a small-scale model of the energy exchanger, which is smaller and often simpler than the full-scale energy exchanger, can be used to predict the performance of the full-scale energy exchanger at different conditions. This paper presents a scaling methodology to investigate a similarity between small-scale and full-scale energy exchangers. The scaling methodology consists of 5 main steps: (1) develop and build a small-scale energy exchanger and a test facility to test the small-scale energy exchanger; (2) test the small-scale energy exchanger under various test conditions; (3) model the couple heat and mass transfer in the energy exchanger, and validate the model with the experimental data; (4) test a full-scale energy exchanger with similar design as the small-scale energy exchanger under various test conditions; and (5) investigate the similarity between the small-scale and full-scale energy exchangers. The similarity between a small-scale single-panel liquid-to-air membrane energy exchanger (LAMEE) and a full-scale LAMEE is investigated in this paper using the scaling methodology. A LAMEE is a novel flat-plate membrane-based energy exchanger where the heat and moisture transfer between air and solution streams through a semi-permeable membrane. The similarity results for the LAMEE show that the small-scale LAMEE effectiveness results can be used to predict the performance of the full-scale LAMEE within ±2% and ±4% uncertainty bounds.